Malnutrition can be defined as the lack of sufficient quantity or quality of nutrients to maintain the body system at some definable level of functioning. It occurs when a person is not receiving, or cannot absorb, the required daily micronutrients.
Its victims are mainly children under the age of 5, and it is visible in only about 2% of all actual cases - despite the image of the starving baby, visible and obvious malnutrition is rare, while invisible malnutrition touches approximately one quarter of the developing world's children. It may be invisible even to mothers, who see their children maintaining normal heights and weights for their age group; but nevertheless it saps a child's energy, lowers his resistance to infection, and holds back his growth. Malnutrition is not caused only by a lack of food (which may be seasonal) but by: infection (diarrhoea and intestinal parasites cause 50% of all malnutrition); by changing from breast milk to commercial substitutes (the mother cannot read the directions for preparation, has neither time nor facilities for proper preparation, and cannot afford adequate amounts); and by improper weaning. Mild to moderate malnutrition, also called chronic undernutrition, is much more common than severe forms, while the severe (recognizable) forms are either due to insufficient protein and calories (marasmus) or to an acute protein loss or deprivation (kwashiorkor). Malnutrition is also a major contributor to disease.
Malnutrition causes a child to withdraw into an inner world, because of the necessity to cease physical activity, and thus retards his mental as well as physical growth; it may cause a malnourished mother to give birth to an underweight baby and to exhaust herself in the vicious cycle of pregnancy, birth, and breastfeeding without adequate recuperation periods; and a malnourished adult man may be forced to reduce his activity at the expense of economic and community development. Ironically, malnutrition can also occur among the wealthy, whose over-nutritious diet, rich in fat and calories, leads to: reduced life expectancy, increased susceptibility to disease (obesity, heart disease, high blood pressure), and reduced productivity.
The number of hungry people in the world has fluctuated between 800 million and 1 billion people for several decades.
Most undernourished people are found in developing countries, with a majority in Asia. Poor nutrition is the cause for approximately half of all child deaths, and the most significant contributor to disease.